Reduced-pressure systems, devices, and methods for treating a tissue site that includes a fistula

ABSTRACT

Systems, methods, and devices are disclosed that involve a fistula-isolating device for use when reduced pressure is applied to a wound bed having a fistula. In one instance, the fistula-isolating device includes an adjustable passageway member and a perimeter member that contracts under reduced pressure and that automatically accommodates wound beds of different heights. In another instance, the fistula-isolating device involves a body shaped as a frustro-conical body that is readily sized for different depth wound beds. Other systems, methods, and devices are presented.

RELATED APPLICATIONS

The present invention claims the benefit, under 35 USC §119(e), of thefiling of U.S. Provisional Patent Application Ser. No. 61/394,999,entitled “Reduced-Pressure Systems, Devices, And Methods For Treating ATissue Site That Includes A Fistula,” filed 20 Oct. 2010, which isincorporated herein by reference for all purposes.

FIELD

The present disclosure relates generally to medical treatment systemsand, more particularly, but not by way of limitation, to systems,devices, and methods for treating with reduced pressure a tissue sitethat involves a fistula.

BACKGROUND

Clinical studies and practice have shown that providing reduced pressurein proximity to a tissue site augments and accelerates the growth of newtissue at the tissue site. The applications of this phenomenon arenumerous, but application of reduced pressure has been particularlysuccessful in treating wounds. This treatment (frequently referred to inthe medical community as “negative pressure wound therapy,” “reducedpressure therapy,” or “vacuum therapy”) provides a number of benefits,which may include faster healing and increased formulation ofgranulation tissue. Typically, when applied to open wounds, reducedpressure is applied to the tissue through a porous pad or other manifolddevice. The porous pad contains cells or pores that are capable ofdistributing reduced pressure to the tissue and channeling fluids thatare drawn from the tissue. When applied subcutaneously, often thereduced pressure is delivered through a manifold that includes channelsand openings in a reduced-pressure delivery apparatus.

A fistula at the tissue site can be problematic with respect to applyingreduced pressure to the tissue site. In general terms, a “fistula” is anabnormal passage that leads from an abscess or hollow organ or part tothe body surface or from one hollow organ or part to another and thatmay be surgically created to permit passage of fluids or secretions. Asused herein, “fistula” includes, without limitation, enteric fistulas,enterocutaneous fistulas, and stomas. If a fistula were located at atissue site that is a wound bed that is being treated and if reducedpressure were applied to the whole tissue site, including the fistula,effluent from the fistula would be drawn onto other portions of thetissue site. This would potentially cause slower healing or variousissues. The situation may be more challenging with an intestinal fistulabecause effluent from an intestinal fistula can be corrosive to thewound bed.

SUMMARY

According to illustrative embodiments herein, systems, methods, anddevices involve a fistula-isolating device for use when reduced pressureis applied to a wound bed having a fistula. In one illustrativeembodiment, the fistula-isolating device includes an adjustablepassageway member and a perimeter member that contracts under reducedpressure and that automatically accommodates wound beds of differentheights. In another illustrative embodiment, the fistula-isolatingdevice involves a body shaped as a frustro-conical body that is readilysized for different depth wound beds.

According to an illustrative embodiment, a system for providing reducedpressure treatment to a wound bed having a fistula includes afistula-isolating device for isolating the fistula in the wound bed, adistribution manifold having a fistula aperture for receiving thefistula-isolating device, a sealing member for covering thefistula-isolating device and the distribution manifold to create asealed space over at least a portion of the wound bed, areduced-pressure source for supplying a reduced pressure, areduced-pressure interface fluidly coupled to the distribution manifold,a reduced-pressure delivery conduit fluidly coupled to thereduced-pressure source and to the reduced-pressure interface, and anostomy appliance fluidly coupled to a first aperture on the first flangemember of the fistula-isolating device. The fistula-isolating deviceincludes the first flange member having a first aperture, a secondflange member having a second aperture, and an adjustable passagewaymember coupled to the first flange member and to the second flangemember. The adjustable passageway member has a passageway substantiallyaligned with the first aperture of the first flange member and thesecond aperture of the second flange member. The adjustable passagewaymember is variably moveable between a retracted position in which theadjustable passageway member has a length L_(R) and an extended positionin which the adjustable passageway member has a length L_(E) and whereinL_(E)>3L_(R). The adjustable passageway member is substantially fluidimpermeable. The fistula-isolating device includes a perimeter memberpositioned substantially around an exterior perimeter of the adjustablepassageway member and between the first flange member and the secondflange member. The perimeter member is configured to contract underreduced pressure.

According to another illustrative embodiment, a fistula-isolating devicefor isolating a fistula in a wound bed undergoing reduced-pressuretreatment includes a first flange member having a first aperture, asecond flange member having a second aperture, an adjustable passagewaymember coupled to the first flange member and to the second flangemember. The adjustable passageway member has a passageway substantiallyaligned with the first aperture of the first flange member and thesecond aperture of the second flange member. The adjustable passagewaymember is variably moveable between a retracted position in which theadjustable passageway member has a length L_(R) and an extended positionin which the adjustable passageway member has a length L_(E) and whereinL_(E)>3L_(R). The adjustable passageway member is substantially fluidimpermeable. The fistula-isolating device also includes a perimetermember positioned substantially around an exterior perimeter of theadjustable passageway member and between the first flange member and thesecond flange member. The perimeter member is configured to contractunder reduced pressure.

According to another illustrative embodiment, a method of providingreduced pressure treatment to a wound bed that has a fistula includesproviding a fistula-isolating device for isolating the fistula in thewound bed undergoing reduced-pressure treatment and disposing adistribution manifold, which has a fistula aperture for receiving thefistula-isolating device, proximate to the wound bed with the fistulaaperture substantially over the fistula. The method further includescovering the fistula-isolating device and the distribution manifold witha sealing member to create a sealed space over at least a portion of thewound bed, providing a reduced-pressure source for supplying a reducedpressure, fluidly coupling the reduced-pressure source to thedistribution manifold, and fluidly coupling an ostomy appliance to thefirst aperture on a first flange member. The fistula-isolating deviceincludes the first flange member having a first aperture, a secondflange member having a second aperture, and an adjustable passagewaymember coupled to the first flange member and to the second flangemember. The adjustable passageway member has a passageway substantiallyaligned with the first aperture of the first flange member and thesecond aperture of the second flange member. The adjustable passagewaymember is variably moveable between a retracted position in which theadjustable passageway member has a length L_(R) and an extended positionin which the adjustable passageway member has a length L_(E) and whereinL_(E)>3L_(R). The adjustable passageway member is substantially fluidimpermeable. A perimeter member is positioned substantially around anexterior perimeter of the adjustable passageway member between the firstflange member and the second flange member. The perimeter member isconfigured to contract under reduced pressure.

According to another illustrative embodiment, a system for providingreduced pressure treatment to a wound bed that has a fistula includes afistula-isolating device for isolating the fistula in the wound bed, adistribution manifold having a fistula aperture for receiving thefistula-isolating device, a sealing member for covering thefistula-isolating device and the distribution manifold to create asealed space over at least a portion of the wound bed, areduced-pressure source for supplying a reduced pressure to the sealedspace, and an ostomy appliance fluidly coupled to the fistula-isolatingdevice. The fistula-isolating device includes a body that issubstantially frusto-conical in shape and has a passageway. Thefistula-isolating device also includes a first end and a second end. Atleast a portion of the body defining the passageway is fluidimpermeable.

According to another illustrative embodiment, a system for providingreduced, pressure treatment to a wound bed that has a fistula includes afistula-isolating device for isolating the fistula in the wound bedundergoing reduced-pressure treatment. The fistula-isolating deviceincludes an adjustable passageway member. The adjustable passagewaymember is configured to move between a retracted position and anextended position and is substantially fluid impermeable. Thefistula-isolating device also includes a perimeter member positionedsubstantially around an exterior perimeter of the adjustable passagewaymember. The perimeter member is configured to contract under reducedpressure. The system also includes a distribution manifold having afistula aperture for receiving the fistula-isolating device, a sealingmember for covering the fistula-isolating device and the distributionmanifold to create a sealed space over at least a portion of the woundbed, a reduced-pressure source for supplying a reduced pressure to thesealed space, and an ostomy appliance fluidly coupled to the adjustablepassageway member.

According to an illustrative embodiment, a system for providing reducedpressure to a wound bed that contains a fistula includes a distributorfor distributing reduced pressure in the wound bed, an isolation devicefor isolating the fistula from other portions of the wound bed, a coverfor providing a fluid seal over the distributor and the isolationdevice, a reduced-pressure source fluidly coupled to the distributor,and a collection vessel fluidly coupled to the passageway of theisolation device for receiving fluids from the fistula. The isolationdevice includes a compressible, fluid-impermeable member, which has afirst end, a second end, and a passageway, and a resilient memberadjacent to the compressible, fluid-impermeable member that is sized andconfigured to bias the first end of the compressible, fluid-impermeablemember away from the second end of the compressible, fluid-impermeablemember.

According to an illustrative embodiment, an ostomy-appliance interfacefor fluidly coupling an ostomy appliance and a fistula isolating deviceincludes an attachment ring having a body and an aperture. Theattachment ring has a first side and a second, patient-facing side. Theostomy-appliance interface further includes a first ostomy-attachmentdevice coupled to the first side of the attachment ring for coupling tothe ostomy appliance, a second ostomy-attachment device coupled to thesecond, patient-facing side for coupling to the fistula isolatingdevice, a first release liner releasably coupled to the firstostomy-attachment device, and a second release liner releasably coupledto the second ostomy-attachment device.

Other aspects, features, and advantages of the illustrative embodimentswill become apparent with reference to the drawings and detaileddescription that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram, with a portion shown in cross section, ofan illustrative embodiment of a system for providing reduced pressuretreatment to a wound bed that includes a fistula;

FIG. 2 is a schematic, perspective view of an illustrative embodiment ofan adjustable passageway member and flange members of afistula-isolating device;

FIG. 3A is a schematic, perspective view of an illustrative embodimentof a fistula-isolating device shown in an extended position;

FIG. 3B is a schematic, perspective view of the fistula-isolating deviceof FIG. 3A shown in the retracted position;

FIG. 4 is a schematic top view of an illustrative embodiment of anostomy-appliance interface;

FIG. 5 is a schematic cross section of the ostomy-appliance interface ofFIG. 4 taken along line 5-5;

FIG. 6 is a schematic, partial perspective, partial cross section of anillustrative embodiment of a fistula-isolating device;

FIG. 7 is a schematic, perspective view of an illustrative embodiment ofa fistula-isolating device;

FIG. 8 is a schematic, plan view of the fistula-isolating device of FIG.7 in a retracted state and with a portion of the first flange removed;

FIG. 9 is a schematic, cross-sectional view of the fistula-isolatingdevice of FIGS. 7-8;

FIG. 10 is a schematic, perspective view of an illustrative embodimentof another fistula-isolating device; and

FIG. 11 is a schematic, perspective view of still another illustrativeembodiment of a fistula-isolating device.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of the illustrative, non-limitingembodiments, reference is made to the accompanying drawings that form apart hereof. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it isunderstood that other embodiments may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theembodiments described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the illustrative embodiments are defined only by the appendedclaims.

Referring now to FIGS. 1-6 and initially to FIG. 1, a system 100 forproviding reduced pressure treatment to a wound bed 102 that includes afistula 104 is presented. The fistula 104 may be, for example, anenterocutaneous fistula. By way of introduction, the system 100 includesa fistula-isolating device 106 for isolating the fistula 104 in thewound bed 102 undergoing reduced-pressure treatment. Thefistula-isolating device 106 fits within a fistula aperture 108 formedin a distribution manifold 110, which is used to provide reducedpressure therapy to the wound bed 102. A sealing member 112 covers thedistribution manifold 110 and the fistula-isolating device 106, and aportion of the patient's epidermis 126 to from a sealed space 114 overthe wound bed 102. A reduced-pressure interface 116 provides fluidcommunication through the sealing member 112 to the sealed space 114. Areduced-pressure delivery conduit 118 fluidly couples thereduced-pressure interface 116 to a reduced-pressure source 120. Anostomy appliance 122 or other collection vessel may be coupled to anostomy-appliance interface 124, or more generally a collection vesselinterface, which is fluidly coupled to the fistula-isolating device 106.In one illustrative embodiment (not explicitly shown), the first flangemember 140 may comprise the ostomy-appliance interface 124.

The wound bed 102 may be through epidermis 126 of the patient 128 andinvolve subcutaneous tissue 130. The system 100 may used on manydifferent types of tissue sites, e.g., bodily tissue of any human,animal, or other organism, including bone tissue, adipose tissue, muscletissue, dermal tissue, vascular tissue, or any other tissue. Treatmentof the wound bed 102 may include removal of fluids, e.g., exudate. Inthe particular illustrative embodiment shown, the fistula 104 is shownfluidly coupling a portion of the patient's 128 bowel 132 to a portionof the wound bed 102. As used herein, “fistula” includes a stoma.

The distribution manifold 110 is sized by the healthcare provider to fitin the wound bed 102, and the fistula aperture 108 is sized toaccommodate the fistula-isolating device 106. The term “manifold” or“distribution manifold” as used herein generally refers to a substanceor structure that is provided to assist in applying reduced pressure to,delivering fluids to, or removing fluids from a tissue site, such as thewound bed 102. Unless otherwise indicated, as used throughout thisdocument, “or” does not require mutual exclusivity. The distributionmanifold 110 typically includes a plurality of flow channels or pathwaysthat distribute fluids provided to and removed from the tissue site,e.g., the wound bed 102, around the distribution manifold 110. In oneillustrative embodiment, the flow channels or pathways areinterconnected to improve distribution of fluids provided or removedfrom the wound bed 102.

The distribution manifold 110 may be a biocompatible material that iscapable of being placed in contact with the wound bed 102 anddistributing reduced pressure to the wound bed 102. Examples ofdistribution manifolds may include one or more of the following withoutlimitation: devices that have structural elements arranged to form flowchannels, such as, for example, cellular foam, open-cell foam, poroustissue collections, liquids, gels, and foams that include, or cure toinclude, flow channels; a porous material; foam; gauze; felted mat; aporous foam, which includes a plurality of interconnected cells or poresthat act as flow channels; a polyurethane, open-cell, reticulated foamsuch as GranuFoam® material from Kinetic Concepts, Incorporated of SanAntonio, Tex. In some situations, the distribution manifold 110 may alsobe used to distribute fluids such as medications, antibacterials, growthfactors, and various solutions to the wound bed 102. Other layers may beincluded in or on the distribution manifold 110, such as absorptivematerials, wicking materials, hydrophobic materials, and hydrophilicmaterials.

In one illustrative embodiment, the distribution manifold 110 or portionthereof may be constructed from bioresorbable materials that do not haveto be removed from a patient's body following use of the system 100.Suitable bioresorbable materials may include, without limitation, apolymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA).The polymeric blend may also include, without limitation,polycarbonates, polyfumarates, and capralactones. The distributionmanifold 110 may further serve in some embodiments as a scaffold for newcell-growth, or a scaffold material may be used in conjunction with thedistribution manifold 110 to promote cell-growth. A scaffold is asubstance or structure used to enhance or promote the growth of cells orformation of tissue, such as a three-dimensional porous structure thatprovides a template for cell growth. Illustrative examples of scaffoldmaterials include calcium phosphate, collagen, PLA/PGA, coral hydroxyapatites, carbonates, or processed allograft materials.

The sealing member 112 covers the distribution manifold 110,fistula-isolating device 106, and a portion of intact epidermis 126. Thesealing member 112 provides a fluid seal to form the sealed space 114.The fluid seal is a seal adequate to maintain reduced pressure at adesired site given the particular reduced-pressure source 120 orsubsystem involved. The sealed space 114 creates a space where reducedpressure may be brought to bear upon the wound bed 102, except theportion isolated by the fistula-isolating device 106. The sealing member112 may be any material that provides a fluid seal. The sealing member112 may be formed from one or more of the following: impermeable;semi-permeable materials; elastomeric materials (e.g., natural rubbers,polyisoprene, styrene butadiene rubber, chloroprene rubber,polybutadiene, nitrile rubber, butyl rubber, ethylene propylene rubber,ethylene propylene diene monomer, chlorosulfonated polyethylene,polysulfide rubber, polyurethane (PU), EVA film, co-polyester, orsilicones); a silicone drape; 3M Tegaderm drape; and polyurethane (PU)drape such as one available from Avery Dennison Corporation of Pasadena,Calif.

An attachment device 134 may be used to hold the sealing member 112against the patient's epidermis 126 or another layer, such as a gasketor additional sealing member. The attachment device 134 may takenumerous forms. For example, the attachment device 134 may be amedically acceptable, pressure-sensitive adhesive that extends about aperiphery, or a portion of, or all of the sealing member 112. Theattachment device 134 may also serve to engage the fistula-isolatingdevice 106.

The reduced-pressure interface 116 may be placed on an aperture 136formed in the sealing member 112 to provide fluid communication to thesealed space 114. In one illustrative embodiment, the reduced-pressureinterface 116 is a T.R.A.C.® Pad or Sensa T.R.A.C.® Pad available fromKCI of San Antonio, Tex. The reduced-pressure interface 116 may take anyform that provides fluid access to the sealed space 114.

The reduced pressure developed by the reduced-pressure source 120 isdelivered through the reduced-pressure delivery conduit 118 to thereduced-pressure interface 116. The reduced-pressure delivery conduit118 may be any medical conduit, single or multi-lumen, for placing thereduced-pressure interface 116 in fluid communication with thereduced-pressure source 120.

The reduced-pressure source 120 may be any device for supplying areduced pressure, such as a vacuum pump, wall suction, integratedmicro-pump, or other source. While the amount and nature of reducedpressure applied to a tissue site, e.g., wound bed 102, will typicallyvary according to the application, the reduced pressure will typicallybe between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa), more typicallybetween −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa), and moretypically still between −75 mm Hg (−9.9 kPa) and −200 mm Hg (−26.6 kPa).For example, and not by way of limitation, the pressure may be −12,−12.5, −13, −14, −14.5, −15, −15.5, −16, −16.5, −17, −17.5, −18, −18.5,−19, −19.5, −20, −20.5, −21, −21.5, −22, −22.5, −23, −23.5, −24, −24.5,−25, −25.5, −26, −26.5 kPa or another pressure. One illustrativeembodiment uses a therapeutic pressure range that is between −75 mm to−175 mm Hg.

Reduced pressure is a pressure less than the ambient pressure at atissue site that is being subjected to treatment. In most cases, thisreduced pressure will be less than the atmospheric pressure at which thepatient is located. Alternatively, the reduced pressure may be less thana hydrostatic pressure at the tissue site, e.g., wound bed 102. Unlessotherwise indicated, values of pressure stated herein are gaugepressures. The reduced pressure delivered may be constant or varied(patterned or random) and may be delivered continuously orintermittently. Although the terms “vacuum” and “negative pressure” maybe used to describe the pressure applied to the tissue site, the actualpressure applied to the tissue site may be more than the pressurenormally associated with a complete vacuum. Consistent with the useherein, an increase in reduced pressure or vacuum pressure typicallyrefers to a relative reduction in absolute pressure.

The fistula-isolating device 106 functionally isolates the fistula 104from other portions of the wound bed 102 so that reduced pressure doesnot attract effluent from the fistula 104 into the distribution manifold110. The fistula-isolating device 106 also functions to contract withthe distribution manifold 110 and to accommodate different depths ofwound beds 102. As suggested by FIGS. 2-3, 6, 7-9, 10, and 11, numerousembodiments of the fistula-isolating device 106 may used as part of thesystem 100.

Referring now primarily to FIG. 1-3B, a couple of illustrativeembodiments of the fistula-isolating device 106 are presented. Thefistula-isolating device 106 may include a first flange member 140having a first flange aperture 142, a second flange member 144 having asecond flange aperture 146, and an adjustable passageway member 148therebetween. The adjustable passageway member 148 is coupled to thefirst flange member 140 and to the second flange member 144 and has apassageway 150 that is substantially aligned with the first flangeaperture 142 and the second flange aperture 146. The adjustablepassageway member 148 is fluid impermeable, which means that theadjustable passageway member 148 substantially restricts or prevents theflow of fluids (liquids or gases).

The fistula-isolating device 106 and, accordingly, the adjustablepassageway member 148 are variably moveable between an extended positionand a retracted position. For example, the fistula-isolating device 106is shown in FIG. 3A in an extended position and is shown in FIG. 3B in aretracted position. In the retracted position, the adjustable passagewaymember 148 has a length L_(R) and in the extended position theadjustable passageway member 148 has a length L_(E). In an illustrativeembodiment the length of the adjustable passageway member 148 in theextended position L_(E) is at least three times that of the length inthe retracted position L_(R), i.e., L_(E)>3L_(R). In other embodimentsthe relationships may be different, e.g., L_(E)>2L_(R), L_(E)>4L_(R),L_(E)>5L_(R), L_(E)>6L_(R), L_(E)>8L_(R), L_(E)>10L_(R), orL_(E)>12L_(R). The fistula-isolating device 106 may have variousdimensions, and in one illustrative embodiment has a retracted length(L_(R)) in the retracted position of approximately one centimeter (1 cm)or less and may have an extended length (L_(E)) in the extended positionof approximately ten centimeters (10 cm) or more.

The fistula-isolating device 106 includes a perimeter member 152positioned substantially around an exterior perimeter 154 of theadjustable passageway member 148 and between the first flange member 140and the second flange member 144. In some embodiments, the perimetermember 152 may be coupled to the first flange member 140 and to thesecond flange member 144 using any known technique, including, withoutlimitation, welding (e.g., ultrasonic or RF welding), bonding,adhesives, or cements. Some embodiments may not include the flangemembers 140, 144 and the perimeter member 152 may be coupled merely tothe exterior perimeter 154.

The perimeter member 152 is configured to contract under reducedpressure. It should be apparent that the perimeter member 152 does notcontract in and of itself under the influence of reduced pressure butindirectly as the sealing member 112 presses upon the perimeter member152. The sealing member 112 presses upon the perimeter member 152 as thesealed space 114 is evacuated by the application of reduced pressure. Insome embodiments, the perimeter member 152 and distribution manifold 110have the same initial height and substantially contract the same amountunder reduced pressure. For example, the distribution manifold 110 mayhave an initial height 156 of h_(d1) when not subjected to reducedpressure, and the fistula-isolating device 106 may have an initialheight h_(f1) when not subjected to reduced pressure. The heights arewith respect to a component in a wound bed 102. Initially, h_(d1) issubstantially equal to h_(f1). Similarly, the distribution manifold 110may have a height h_(d2) when subjected to reduced pressure at a firsttherapeutic pressure (for example, but not by way of limitation, −75 to−175 mm Hg), and the fistula-isolating device 106 may have a heighth_(f2) when subjected to reduced pressure at the first therapeuticpressure. The heights may be substantially the same, i.e., h_(d2) issubstantially equal to h_(f2).

In some illustrative embodiments, the perimeter member 152 is made fromthe same material as the distribution manifold 110. For example, in oneillustrative embodiment, both the distribution manifold 110 and theperimeter member 152 are made from an open cell foam, such as aGranuFoam® material from Kinetic Concepts, Incorporated of San Antonio,Tex. The perimeter member 152 may be made from other substances thatallow fluid flow and that function to help the adjustable passagewaymember 148 adjust to or take on different heights. For example, theperimeter member 152 may be formed from one or more of the following: afluid permeable material that functions as an isotropic spring, aresilient material (e.g. a foam or elastic member), or other materialmay be used. The perimeter member 152 and adjustable passageway 148substantially rise and fall with the movement of the distributionmanifold 110. In other words, the perimeter member 152 and adjustablepassageway 148 substantially mimic the movement of the distributionmanifold 110. The perimeter member 152, in one illustrative embodiment,may be relatively small pieces of foam or other manifold material andmay be loosely placed around the adjustable passageway 148. Similarly,in one embodiment, the distribution manifold 110 may be an array ofpieces of foam and the opening in which the fistula-isolating device 106is disposed may be an opening or clearance in the array of pieces offoam. “Around,” as used herein, means in the relative vicinity of anobject and surrounding the object over at least 140 degrees and moretypically over 180 degrees.

The adjustable passageway member 148 may be made from a thin flexiblematerial that may be compressed or extended with the perimeter member152. The flexible material may be, without limitation, a medical gradepolymer or elastomers such as Silicone, polyurethane, TPE, TPU, PEBAX,TPO, nitrile, butyl and EVA. The adjustable passageway member 148 maycomprise an annular wall member 158 having a thickness 0.25 mm to 3 mmor more. In one illustrative embodiment, the annular wall member 158 isless than 1 mm thick. The annular wall member 158 may contain bellows160 (FIGS. 2 and 6) or collapsible folds 162 (FIGS. 7-9) that readilyallow the fistula-isolating device 106 to expand and retractlongitudinally along with the perimeter member 152. The second flangemember 144 may include grooves 164 or visual indicia (by analogy see 190in FIG. 7) to facilitate cutting the flange member 144 to a smaller sizeif a smaller flange member is desired near the fistula 104.

The illustrative embodiment of the adjustable passageway 148 of FIG. 2varies some from the illustrative embodiment of the adjustablepassageway 148 included in FIGS. 3A and 3B mainly in the thickness ofthe adjustable passageway 148 and the size of the flange members 140,144 that have been coupled. The embodiment of the adjustable passageway148 of FIGS. 3A-3B may rely exclusively on pressure on the second flangemember 144 that is delivered by the perimeter member 152 to provide aseal against the wound bed 102. In this embodiment, the adjustablepassageway 148 may not carry a force structurally itself. In contrast,the embodiment of the adjustable passageway 148 of FIG. 2 may use anattachment device, e.g., ostomy paste, or other device, and may carrysome of the structural forces such as providing a compressive force onthe perimeter member 152. In other words, in some embodiments, the freelength of the adjustable passageway 148 may be less than the lengthrealized when the fistula-isolating device 106 is in the extendedposition. Accordingly, a tensile force is applied between the flanges140, 144 and thereby delivers a compressive force to the perimetermember 152.

Referring again to FIGS. 1-3B, the first flange member 140, secondflange member 144, and adjustable passage way 148 provide a passageway150 through which any effluent from the fistula 104 passes withoutinterfering with the reduced pressure therapy administered by thedistribution manifold 110 to the wound bed 102. To receive the effluent,the ostomy appliance 122 is fluidly coupled to the first flange aperture142 of the passageway 150 by the ostomy-appliance interface 124. Itshould be apparent that the fluid coupling of the ostomy-applianceinterface 124 to the first flange aperture 142 is through theostomy-interface aperture 182 in the sealing member 112. The ostomyappliance 122 may be any form of device for receiving effluent from thefistula 104. For example, the ostomy appliance may be an off-the-shelfostomy pouch, such as those available from Combitech, Coloplast, orHollistser.

The ostomy-appliance interface 124 may be take numerous forms, such as abase plate 166 (FIG. 6) attached to the first flange member 140, or, asshown in FIG. 1, an attachment ring 168 with a first ostomy-attachmentdevice 170 and a second ostomy-attachment device 174. In oneillustrative embodiment, the ostomy-appliance interface 124 may be astomahesive wafer. The ostomy-appliance interface 124 may also be a snapon collar or base plate, an adhesive skirt, or other device. In oneillustrative embodiment, the ostomy-appliance interface 124 is a thinfilm, e.g., a drape-like material, and in others a thicker body.

Referring now primarily to FIGS. 1 and 4-5, an illustrative embodimentthat uses the attachment ring 168 as the ostomy-appliance interface 124will be presented. The first ostomy-attachment device 170 may be on afirst side 172 of the attachment ring 168, and the secondostomy-attachment device 174 may be on the second, patient-facing side176 of the attachment ring 168. The ostomy-attachment devices 170, 174may be, for example, a pressure sensitive adhesive, cohesive seal (e.g.,an Eakin's Ring), or a paste strip (e.g., Coloplast® Ostomy PasteStrip). In a before-use state, the first ostomy-attachment device 170may be covered by a first release liner 178, and the secondostomy-attachment device 174 may be covered by a second release liner180. The attachment ring 168 has an ostomy-interface aperture 182 thatis positioned, at least in part, over the passageway 150.

Referring now generally to FIG. 6, in another illustrative embodiment,the ostomy-appliance interface 124 may include the base plate 166 thatmay directly attach to a device on an ostomy appliance (not explicitlyshown). Other aspects of the fistula-isolating device 106 of FIG. 6 areanalogous to those previously presented.

Referring now to FIGS. 1-6, according to one illustrative embodiment, inoperation, the healthcare provider sizes the distribution manifold 110to be approximately the size of the wound bed 102. A fistula aperture108 is formed in the distribution manifold 110 at the location thatsubstantially aligns with the fistula 104. In some embodiments, thefistula aperture 108 may be preformed and then aligned with the fistula104 before the distribution manifold 110 is cut to fit the wound bed102. The distribution manifold 110 is placed into the wound bed 102 withthe fistula aperture 108 over the fistula 104. The fistula-isolatingdevice 106 may be placed inside of the fistula aperture 108 before orafter development of the distribution manifold 110. In some embodiments,the second flange member 144 is positioned directly against a portion ofthe wound bed 102 and will ultimately form the fluid seal using forcefrom the perimeter member 152. In other embodiments, a sealing device,such as a stoma paste, adhesive, hydrocolloid, hydrogel, silicone gel,or other substance may be used to form a seal with the second flangemember 144 and the wound bed 102 around the fistula 104.

The sealing member 112 may be placed over a portion of the intactepidermis 126, distribution manifold 110, and fistula-isolating device106 to form the sealed space 114 over the wound bed 102. The attachmentdevice 134 may be used to help provide a fluid seal between the sealingmember 112 and the epidermis 126. If not already formed, the aperture136 may be formed on the sealing member 112 and the reduced-pressureinterface 116 applied through the aperture 136 to provide fluidcommunication to the sealed space 114. If not already made, anostomy-interface aperture 182 may be formed in the sealing member 112over the passageway 150 of the fistula-isolating device 106. Theostomy-appliance interface 124 may be applied to the ostomy-interfaceaperture 182 and the ostomy appliance 122 attached to theostomy-appliance interface 124.

With respect to the ostomy-appliance interface 124 shown in FIGS. 4-5,the ostomy-appliance interface 124 may be attached by removing thesecond release liner 180 to expose the second ostomy-attachment device174 and placing the ostomy-appliance interface 124 onto the first sideof the sealing member 112 proximate to the passageway 150. The firstrelease liner 178 may be removed to expose the first ostomy-attachmentdevice 170, and then the ostomy appliance 122 may be attached using thefirst ostomy-attachment device 170. The ostomy appliance 122 is appliedwith an aperture 123 of the ostomy appliance 122 over theostomy-appliance interface 124.

The reduced-pressure source 120 may be coupled to the reduced-pressureinterface 116 using the reduced-pressure delivery conduit 118. Thereduced-pressure source 120 is activated and reduced pressure isdelivered through the reduced-pressure delivery conduit 118 into thesealed space 114, which includes the distribution manifold 110. Thedistribution manifold 110 contracts under the influence of reducedpressure. It should be apparent that the distribution manifold 110 doesnot contract in and of itself under reduced pressure, but as the sealedspace 114 is evacuated by the reduced pressure and the sealing member112 applies a compressing force on the distribution manifold 110. Inaddition, under the influence of reduced pressure in the sealed space114, the perimeter member 152 of the fistula-isolating device 106 alsocontracts for the same reasons. Through the influence of the contractionof the perimeter member 152 directly, which may be coupled to the flangemembers 140, 144, or through the action of the sealing member 112 movingwith the contraction of the distribution manifold 110, thefistula-isolating device 106 compresses and may substantially match thecompression of the distribution manifold 110.

It should be noted that the flexibility of the second flange member 144and the perimeter member 152 allow various shaped wound beds 102 to bereadily accommodated by the fistula-isolating device 106. Moreover, itshould be noted that the vertical height adjustment of thefistula-isolating device 106 is automatic in that the fistula-isolatingdevice 106 will respond with the distribution manifold 110. Thus, if thedistribution manifold 110 has an initial height H_(d1) when notsubjected to reduced pressure and the fistula-isolating device 106 hasan initial height H_(f1), then H_(d1) is substantially equal to H_(f1),and under reduced pressure, the height of the distribution manifold isH_(d2) and the height of the fistula-isolating device 106 is H_(f2),then H_(d2) is substantially equal to H_(f2).

In some embodiments, e.g., those that include the adjustable passageway148 of the type shown in FIG. 2, as the fistula-isolating device 106compresses, the bellows 160 of the adjustable passageway member 148compress, or if the collapsible folds (see FIG. 7) are used, thecollapsible folds collapse in order for the fistula-isolating device 106to assume the position under the influence of reduced pressure. With thesystem 100, reduced pressure reaches all of the wound bed 102 in thesealed space 114 except for the portion isolated by thefistula-isolating device 106. It should also be noted that the system100 may be deployed relatively quickly and requires only minimal cuttingand customization by the healthcare provider. The system 100 may protectthe epidermis 126 and the wound bed 102, contain effluent from thefistula 104, and provide patient mobility and comfort.

Referring now primarily to FIGS. 1 and 7-11, a fistula-isolating device106 for isolating a fistula 104 in a wound bed 102 undergoingreduced-pressure treatment as part of a system 100 includes a body 184.The body 184 of the fistula-isolating device 106 is substantiallyfrustro-conical in shape and has a passageway 150 with a first end 186and a second end 188. At least a portion of the body 184 defines thepassageway 150 and is fluid impermeable.

Referring now particularly to FIGS. 7-9, the fistula-isolating device106 has the body 184 formed with collapsible folds 162 that allow thefistula-isolating device 106 to collapse to a one-fold high level asshown in FIG. 9 when in a retracted position. FIGS. 8 and 9 are shownwithout an optional extended portion 143 (FIG. 7) of the second flange144. While the dimensions may vary in different embodiments, in oneembodiment, the fully collapsed height of the fistula-isolating device106 is approximately one centimeter and the extended position isapproximately 10 centimeters. The collapsible folds 162 also allow thebody 184 to go to an extended position as shown in FIG. 7. The body 184may be formed with or have coupled a first flange member 140 and asecond flange member 144. The second flange member 144, which is placedproximate to a portion of the wound bed 102, may be cut to the size ofthe fistula 104 opening, and visual indicia 190 may be included to showvarious possible cut patterns for different sizes as shown in FIG. 7. Inother embodiments, e.g., FIGS. 10-11, no flange member may be included.The retracted position of the fistula-isolating device 106, among otherthings, may facilitate packaging and accommodate small depth wound beds.

The body 184 may have a first portion 163 having an external radius R₁,a second portion 167 having a second radius R₂, and a third portion 169having a third radius R₃, wherein R₁>R₂>R₃. Similarly, additionalportions with varying radii may be included as shown. This again is anarrangement that allows the collapsible folds 162 to fully collapse downto a single layer as shown in FIG. 9. In some embodiments, the firstflange member 140 may be placed in the wound bed 102 and in anotherembodiment, the second flange member 144 may be placed in the wound bed102.

Referring now primarily to FIGS. 1, and 7-9, according to oneillustrative embodiment, in use, the distribution manifold 110 is sizedand prepared for application against the wound bed 102 as previouslypresented. The fistula aperture 108 may be formed through thedistribution manifold 110 to substantially accommodate thefistula-isolating device 106. In this embodiment, the second flangemember 144 may include visual indicia 190, which may be used to help thehealthcare provider to cut a portion of the second flange member 144 toaccommodate the desired size around the fistula 104. Once the secondflange member 144 has been sized as desired with respect to thebeginning of the passageway 150, the second flange member 144 is placedagainst the wound bed 102 with the passageway 150 centered on thefistula 104.

The second flange member 144 may or may not be secured against the woundbed 102 using a device, such ostomy paste or those previously mentioned.The seal between the wound bed 102 and the second flange member 144 (orfirst flange member 140) may be formed in some embodiments only usingthe pressure that is asserted on the flange member 144 through theperimeter member 152. Pieces of distribution manifold 110 may be appliedin the fistula aperture 108 between the flange members 140 and 144 toserve as a perimeter member, e.g., perimeter member 152 in FIG. 1. Theremaining steps for applying the fistula-isolating device 106 areanalogous to those previously presented with respect to FIGS. 1-6. Itshould be noted that with the design of the fistula-isolating device 106of FIGS. 7-9, the fistula-isolating device 106 will contract or extendwith the distribution manifold 110. Moreover, the fistula-isolatingdevice 106 may take a variable position from a retracted position (FIG.9) to an extended position (FIG. 7).

Referring now primarily to FIG. 10, another illustrative embodiment of afistula-isolating device 106 formed as a body 184 is presented. Thefistula-isolating device has a frusto-conical shape or cone shape. Thebody 184 does not have flange members and is formed of a foam with apassageway 150 that is fluid impermeable. Visual indicia 165 may beprinted on an exterior of the body 184 to facilitate cutting to size forvarious depths of wound beds 102. In some embodiments, the body 184 maybe perforated to facilitate sizing by hand. The perforations may alloweasy tearing of the body 184 to size the fistula-isolating device 106.The portion of the body 184 that renders the passageway 150 impermeablemay not be perforated. The frustro-conical shape of thefistula-isolating device 106 may be made from a closed-cell foam or anopen-cell foam with an impermeable layer on the passageway 150. The body184 of this illustrative embodiment does not have bellows or collapsiblefolds and is not made generally to retract.

Referring now to FIGS. 1 and 10, the application of the system 100 usingthe fistula-isolating device 106 shown in FIG. 10 is analogous to thosepreviously presented. In this particular embodiment, the body 184 may becut using visual indicia 165 to accommodate a particular depth of thewound bed 102. Thus, for a more shallow wound, the cut may be madecloser to a second end 188. After cutting as desired, the second end188, and in particular the opening to the passageway 150, is placedaround the fistula 104 through the fistula aperture 108 in thedistribution manifold 110. The second end 188 may be sized withdifferent opening sizes. For example, and not by way of limitation, inone embodiment, the opening is 0.25 inches (6.35 mm) and in anotherembodiment is 2 inches (50.8 mm). The opening may take other sizes aswell. The length of the fistula-isolating device 106 may be any lengthdesired and the healthcare provider may cut the fistula-isolating device106 to the desired length. In one illustrative embodiment, thefistula-isolating device 106 has a longitudinal length of 4 to 5 inches(10.2 to 12.7 cm) but could be made longer or shorter.

The body 184 may be flexible enough to accommodate irregular shapedfistulas 104 and wound beds 102 and yet may be semi-rigid enough toprevent collapse under normal usage. Other aspects of applying thefistula-isolating device 106 of FIG. 10 are analogous to thosepreviously discussed. It should be noted that the foam of the body 184allows for accommodation of uneven wound beds 102 and other issues. Thebody 184 is highly customizable since the healthcare provider can easilycut the body 184 to size and can cut portions of the body 184 to betterfit a wound bed 102. An inner surface of the passageway 150 isimpermeable and so effluent from the fistula is carried through thepassageway 150 and ultimately to the ostomy appliance 122.

Referring now primarily to FIGS. 1 and 11, another illustrativeembodiment of a fistula-isolating device 106 is presented. Thefistula-isolating device 106 is made from a medical polymer and hassteps 161 and no flange members. The fistula-isolating device 106includes a passageway 150. Visual indicia 165 may be included forsizing. The fistula-isolating device 106 of FIG. 11 may be applied in asystem 100 in a manner analogous to those previously presented. In thisembodiment, however, the fistula-isolating device 106 is sized bycutting the body 184 along a step 161 or other visual indicia (analogousto 165 in FIG. 9). The visual indicia 165 may be included to help withsizing for the depth of the wound bed 102. Once sized, the second end188 is typically placed around the fistula 104. It should be noted, thatin this and other embodiments, the larger opening on the first end 186may be applied around the fistula 104 in some situations. Thefistula-isolating device 106 may be formed from a material that isflexible enough to accommodate irregular shaped fistulas 104 and woundbeds 102 and yet semi-rigid enough to prevent collapse under normalusage.

In one illustrative embodiment, the fistula-isolating device 106 and theostomy-appliance interface 124 may be contained within a single kit (notshown). The kit may have molded compartments to protect, for example,the flange members 140, 144 of the fistula-isolating device 106 for theembodiments of FIGS. 1-3B and 6-9. The kit accommodates storage andapplication by the healthcare provider.

According to one illustrative embodiment, the reduced-pressure source120 may be micro-pump that is located at least partially in the sealedspace 114. An inlet (not shown) may provide reduced pressure to thesealed space and a vent (not shown) may be used to exhaust positivepressure to an exterior of the sealing member 112. The reduced-pressureinterface in such an embodiment is the inlet from the micro-pump.

Referring to FIGS. 2 and 3A, in another illustrative embodiment, theadjustable passageway member 148 may be formed with the ability tostretch and have the longitudinal dimension of the adjustable passagewaymember 148 modified, but has a relatively greater rigidity in a radialdirection. The rigidity in the radial direction may help maintain thesize of the passageway 150 even when the sealed space is subject toreduced pressure and pull outwards on the adjustable passageway member148.

Although the present invention and its advantages have been disclosed inthe context of certain illustrative, non-limiting embodiments, it shouldbe understood that various changes, substitutions, permutations, andalterations can be made without departing from the scope of theinvention as defined by the appended claims. It will be appreciated thatany feature that is described in connection to any one embodiment mayalso be applicable to any other embodiment. The fistula-isolatingdevices 106 herein are analogous in many respects in each figure andaccordingly, some parts are labeled in later figures but not furtherdiscussed.

It will be understood that the benefits and advantages described abovemay relate to one embodiment or may relate to several embodiments. Itwill further be understood that reference to “an” item refers to one ormore of those items. As used herein, substantially means at least withinten percent.

The steps of the methods described herein may be carried out in anysuitable order, or simultaneously where appropriate.

Where appropriate, aspects of any of the embodiments described above maybe combined with aspects of any of the other embodiments described toform further examples having comparable or different properties andaddressing the same or different problems.

As will be appreciated by the reader, each of the embodiments offistula-isolating devices 106 described herein provide a passageway 148through a region of reduced pressure 114 being utilized to treat a woundbed 102 such that effluent can be removed from that fistula 104 withoutentering the region of reduced pressure 114. The fistula-isolatingdevices 106 therefore provide a means for isolating part of a regionunder a sealing member 112 to allow extraction of effluent from afistula 104. To accommodate changes in the distance between the woundbed 102 and the sealing member 112 the fistula-isolating device 106 mayhave a variable length, and may be provided with a resilient member 152acting to extend the fistula-isolating device 106. Alternatively, thefistula-isolating device 106 may be formed of a resilient material.

It will be understood that the above description of preferredembodiments is given by way of example only and that variousmodifications may be made by those skilled in the art. The abovespecification, examples and data provide a complete description of thestructure and use of exemplary embodiments of the invention. Althoughvarious embodiments of the invention have been described above with acertain degree of particularity, or with reference to one or moreindividual embodiments, those skilled in the art could make numerousalterations to the disclosed embodiments without departing from thescope of the claims.

1. A system for providing reduced pressure treatment to a wound bed thatincludes a fistula, the system comprising: a fistula-isolating devicefor isolating the fistula in the wound bed undergoing reduced-pressuretreatment, the fistula-isolating device comprising: a first flangemember having a first aperture, a second flange member having a secondaperture, an adjustable passageway member coupled to the first flangemember and to the second flange member, the adjustable passageway memberhaving a passageway substantially aligned with the first aperture of thefirst flange member and the second aperture of the second flange member,wherein the adjustable passageway member is variably moveable between aretracted position in which the adjustable passageway member has alength L_(R) and an extended position in which the adjustable passagewayhas a length L_(E) and wherein L_(E)>3L_(R), wherein the adjustablepassageway member is substantially fluid impermeable, and a perimetermember positioned substantially around an exterior perimeter of theadjustable passageway member between the first flange member and thesecond flange member; a distribution manifold having a fistula aperturefor receiving the fistula-isolating device; a sealing member forcovering the fistula-isolating device and the distribution manifold tocreate a sealed space over at least a portion of the wound bed, whereinthe sealing member has an ostomy-interface aperture fluidly coupled tothe adjustable passageway; a reduced-pressure source for supplying areduced pressure; a reduced-pressure interface fluidly coupled to thedistribution manifold; a reduced-pressure delivery conduit fluidlycoupled to the reduced-pressure source and to the reduced-pressureinterface; and an ostomy appliance fluidly coupled to the first apertureon the first flange member of the fistula-isolating device.
 2. Thedevice of claim 1, wherein the fistula-isolating device furthercomprises an ostomy-appliance interface coupled to the first flangemember.
 3. The system of claim 1, wherein the distribution manifold hasan initial height h_(d1) when not subjected to reduced pressure, whereinthe fistula-isolating device has an initial height h_(F1) when notsubjected to reduced pressure, and wherein h_(d1) is substantially equalto h_(F1).
 4. The system of claim 1, wherein the distribution manifoldhas an initial height h_(d1) when not subjected to reduced pressure; thefistula-isolating device has an initial height h_(F1) when not subjectedto reduced pressure and h_(d1) is substantially equal to h_(F1); thedistribution manifold has a height h_(d2) when the sealed space issubjected to reduced pressure in a first therapeutic pressure range; thefistula-isolating device has a height h_(F2) when the sealed space issubjected to reduced pressure at the first therapeutic pressure and thesealing member delivers a force to the first flange member, and whereinh_(d2) is substantially equal to h_(F2).
 5. The system of claim 1,wherein the adjustable passageway member comprises an annular wallmember having a thickness less than 1 millimeter.
 6. The system of claim1, wherein the perimeter member comprises a first material anddistribution manifold comprises the first material.
 7. The device ofclaim 1, wherein the adjustable passageway member comprises an annularwall having bellows.
 8. The device of claim 1, wherein the adjustablepassageway member comprises an annular wall having collapsible folds. 9.The device of claim 1, wherein when in the extended position, theadjustable passageway member has a length L_(E) that is six timesgreater than the retracted position (L_(E)>6L_(R)).
 10. The device ofclaim 1, wherein when in the extended position, the adjustablepassageway member has a length L_(E) that is ten times greater than theretracted position (L_(E)>10L_(R)).
 11. The device of claim 1, whereinthe perimeter member is fluid permeable.
 12. A fistula-isolating devicefor isolating a fistula in a wound bed undergoing reduced-pressuretreatment, the fistula-isolating device comprising: a first flangemember having a first aperture; a second flange member having a secondaperture; an adjustable passageway member coupled to the first flangemember and to the second flange member, the adjustable passageway memberhaving a passageway substantially aligned with the first aperture of thefirst flange member and the second aperture of the second flange member;wherein the adjustable passageway member is variably moveable between aretracted position in which the adjustable passageway member has alength L_(R) and an extended position in which the adjustable passagewaymember has a length L_(E) and wherein L_(E)>3L_(R); wherein theadjustable passageway member is substantially fluid impermeable; and aperimeter member positioned substantially around an exterior perimeterof the adjustable passageway member between the first flange member andthe second flange member.
 13. The device of claim 12, wherein theadjustable passageway member comprises an annular wall having bellows.14. The device of claim 12, wherein the adjustable passageway membercomprises an annular wall having collapsible folds.
 15. The device ofclaim 12, wherein when in the extended position, the adjustablepassageway member has a length L_(E) that is six times greater than theretracted position (L_(E)>6L_(R)).
 16. The device of claim 12, whereinwhen in the extended position, the adjustable passageway member has alength L_(E) that is ten times greater than the retracted position(L_(E)>10L_(R)).
 17. The device of claim 12, further comprising anostomy-appliance interface formed on the first flange member.
 18. Thedevice of claim 12, wherein the perimeter member is fluid permeable. 19.(canceled)
 20. (canceled)
 21. (canceled)
 22. (canceled)
 23. A system forproviding reduced pressure treatment to a wound bed that includes afistula, the system comprising: a fistula-isolating device for isolatingthe fistula in the wound bed undergoing reduced-pressure treatment, thefistula-isolating device comprising: a body that is substantiallyfrusto-conical in shape and having passageway and having a first end anda second end, and wherein at least a portion of the body defining thepassageway is fluid impermeable; a distribution manifold having afistula aperture for receiving the fistula-isolating device; a sealingmember for covering the fistula-isolating device and the distributionmanifold to create a sealed space over at least a portion of the woundbed, wherein the sealing member has an ostomy-interface aperture; areduced-pressure source for supplying a reduced pressure to the sealedspace; and an ostomy appliance fluidly coupled to the fistula-isolatingdevice.
 24. The system of claim 23, wherein the fistula-isolating devicefurther comprises visual indicia on an exterior of the frusto-conicalbody showing where sizing cuts may be made.
 25. The system of claim 23,wherein the body has a first portion having an external radius R₁, asecond portion having a second radius R₂, and a third portion having athird radius R₃, wherein R₁>R₂>R₃. 26.-54. (canceled)